Speed controlled brake



De. 26, 1939. c. c. FARMER SPEED CONTROLLED BRAKE Filed Feb. 19, 1938 t., ATTORNEY INVENTOR ELYDE E. FARMER BY Patented Dec. 26, 1939 SPEED CONTROLLED yBRAKE Clyde C. Farmer, Pittsburgh, Pa., assigner to 'The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application February 19, 1938,v Serial N0. 191,499

a Claims.

This invention relates to speed-controlled brakes and particularly to brake equipment for vehicles, such as railway cars, and trains, in which the degree of application of the brakes on 5 the Vehicle or car is varied automatically upon variations in the speed of the Vehicle.

It is a fact well understood by those skilled in the art that in order to prevent' the excessive application of the brakes on vehicle wheels and the consequent locking and sliding thereof, it is necessary to relieve or reduce the degree of` application of the brakes as the speed of the vehicle reduces. In the case of railway cars and trains, various types of brake control equipment have been proposed for automatically reducing the degree of application of the brakes on a car as the speed reduces.

It is an object of my invention to provide a novel arrangement for automatically reducing the degree of application of the brakesas the speed of the vehicle or car reduces.

More specifically, it is an object of my invention to provide a Vehicle brake equipment having u a novel arrangement, including a centrifuge de- ?0 vice driven according to the vspeed of the Vehicle,

for automatically varying the degree of application of the brakes as the speed of the vehicle varies.

The above objects, and other objects of my inventio-n which will be made apparent hereinafter, are accomplished by means of an illustrative embodiment of my invention which will be described subsequently and which is shown in the accompanying drawing, wherein,

Fig. l is a diagrammatic View, with parts thereof in section, of a brake equipment embodying my invention, and

Fig. 2 is a diagrammatic view, showing the manner in which the centrifuge device of Fig. l 40 may be operated. v

Description a centrifuge device I4, both of the devices I3 and It being effective to cause operation ofthe relay valve device II.

Considering the parts of the equipment in greater detail, the relay valve device I I comprises scribed land 'claimed in Patent 2,096,491 to E. E.

Hewitt. Briefly, the valve mechanism -comprises a mai'n supply valve 2li in lthe form of a valve piston, a so-called pilot supply valve 25 carried' by the main supply valve Zbl, a main release valve 26, and a pilot release valve 21 associated with the main release valve 26.

The main supply valve 24 is normally urged into seated relation on a valve seat formed in the casing by a coil spring 29 and, when seated, closes communication between an annular chamber 3l at the outer seated area thereof and the pressure chamber I9. The annular chamber 3lv is constantly connected to and charged with fluid under pressure from the main reservoir l2 through a supply pipe and passage 33. A chamber 34 at the back of the main'supply valve 2li is connected throughV a passage 35 to the annular chamber 3| and a choke 36 is provided in the passage 35 for restricting Vthe rate of flow of fluid under pressure from the annular chamber 3l to the chamber 34 for a purpose to be presently `made apparent. l l

The pilot supply valve 25 is of thepoppet type and has a fluted stem which extends slidably through a suitable bore in the main supply valve 24 into the pressure chamber i9, the pilot valve 25 beingcontained within the chamber 313. Normally the pilot supply valveA 25 is yieldingly urged into seated relation on its associated valve seat formed on the main supply valve 2d lby a coil spring 38 contained in the chamber 34 concentrically within the coil spring 29.

The main release valve itis of the poppet type and has a tubular stern which operates slidably in a suitable `bore 3&3 which opens into the pressure chamber I9. rlhe bore 39 lis also open to atmosphere through an exhaust passage and port ll and when the main release valve '6 fis unseated from its associated valve seat, the pressure chamber I9 is connected to atmosphere through the exhaust passage and Aport tl.

The pilot release valve 27 is of the poppet type and is carried on a rod or stem 4S which extends in slidable relation through the longitudinal passage Wthin the stem of the main release Valve 26,

the pilot release valve 21 being adapted to seat on the end of the main release valve 26 to close the connection between the perssure chamber I9 and a chamber 45 at the inner end of the stem of the main release valve through the central longitudinal passage in the stem of the main release valve. A restricted port 4B is provided in the stem of the release valve 2S to enable the release of fluid under pressure from the chamber 45 to atmosphere by way of the exhaust passage 4 l.

Operation of the valves 24, 25, 26 and 21 is effected by means of a lever 48 which is pivoted intermediate the ends thereof on a plunger 49 slidably mounted in the casing. One end of the plunger 49 is provided with a flange 5l against which a compression spring 52 acts to urge the plunger 49 in the right-hand direction, as viewed in Fig. l.

A stop screw 53 is arranged, as shown, to be engaged by the upper end of the lever 48 as it moves in the right-hand direction so that the lower end of the lever 48, which is bifurcated and straddles a reduced portion of the shaft 43 carrying the pilot release valve 21, is urged in the right-hand direction to unseat the pilot release valve 21 from the main release valve 28. The shaft or stem 43 is provided'at the end thereof within the chamber 45 with a nut 55 which engages the end of the stem of the main release valve 26 and causes shifting of the main release valve 26 away from its associated valve seat in response to movement of the shaft 43 in the right-hand direction.

Interposed between the upper end of the lever 48 and the end of the uted stem of the pilot supply valve 25 is a spacer in the form of a short rod 51 which is slidably mounted in the casing in coaxial relation to the fluted stern of the pilot supply valve 25.

The diaphragm portion of the relay valve device Il comprises a plurality of movable abutments or diaphragrns 6i, 62, 63 and 64 arranged in spaced coaxial relation with each other and in axial alignment with the plunger 49, the diaphragms being suitably clamped along the periphery thereof within the casing.

The effective pressure areas of the diaphragms 6| and 62 may have any desired ratio, such as a two-to-one ratio. The diaphragms 63 and 84 are of the same effective pressure areas and, while indicated as of substantially the same effective pressure area as the diaphragm B2, may be of different area with respect thereto.

The arrangement of the diaphragms 6|, E2, 63 and 64 in the casing of the relay valve device Il is such as to form at the outer face of the largest diaphragm 6I a chamber E5 which is constantly open to the pressure chamber I9 through a relatively large passage 56 and also to form, between the largest diaphragm l and the adjacent diaphragm 52, a chamber 61 which is constantly open to atmosphere through an atmospheric port 68. The arrangement of the diaphragms is furthere such that a chamber 69 is formed between the diaphragms 82 and 63 and also a chamber 1l at the outer facey of the diaphragm 64, the two chambers 69 and 1l being in constant communication through a relatively large passage 12. A chamber 13 is formed between the two diaphragrns 53 and $4 and is constantly open to atmosphere through a large opening 14 in the casing, through which opening an operating lever 15, associating the centrifuge device I4 and the relay valve device Il is arranged to extend as presently further described.

Afxed to the outer face of the largest diaphragm 8l within the chamber 65, preferably without perforating the diaphragm, is a follower disk 18 having a rounded projection 19 which engages the iiange 5l at the end of the plunger 49.

Afxed to the opposite face of the largest diaphragm 5| within the chamber G1 is another follower plate or disk 8l which is engaged by a suitable follower disk 82 affixed to the adjacent face of the diaphragm 62, A minimum spacing is thus maintained between the two diaphragms 5l and 82 and independent movement of the diaphragms is permitted.

In a similar manner, suitable follower disks 83 and 84 are affixed to the diaphragme 62 and 63, respectively, within the chamber 59 preferably without perforating the diaphragme, the two follower disks being arranged to maintain at least a minimum spacing between the diaphragms 52 and B3 and permit independent movement of the diaphragms.

Interposed between the diaphragms 63 and 84 within the chamber 13 is a spacer 85, of spool shape, having a flange 85 at one end ailixed to the diaphragm 53 preferably without perforating the diaphragm, and a flange 81 at the opposite end affixed to the diaphragm 64 preferably without perforating the diaphragm, the two flanges 85 and 81 being connected by an intervening stem 88.

The lever 15 is pivoted between the ends thereof on the casing, as by a pin 9|, fixed at a point within the opening 14 of the casing. The lower end of the lever 15 is bifurcated to straddle the stem 88 of the spool shaped spacer 85 and a pin 93, which extends transversely through the stem 88 and through suitable slotted openings 94 at the lower bifurcated end of the lever 15, serves to pivotally connect the lever to the stern 88.

When the outer end of the lever 15 is shifted in the right-hand direction, a force is exerted on the diaphragms urging them and accordingly the plunger 49 in the left-hand direction. In a similar manner, when fluid under pressure is supplied to the chamber 69 between the daphragms 62 and 63, the force of the fluid pressure is exerted on the diaphragm 52 to also urge the diaphragms 62 and 6l and accordingly the plunger 49 in the left-hand direction.

Upon the shifting of the plunger 49 of the relay valve device H in the left-hand direction from the position shown, the lever 48 is rst pivoted about its upper end in a clockwise direction to effect successive seating of the pilot release valve 21 and the main release valve 26, the upper end of the lever 48 being held between the stop screw 53 and the spacer rod 51 by the force of the spring 38 acting on the pilot supply valve 25. When the main release valve 26 is seated, further movement of the lower bifurcated end of the lever 48 is stopped and the lever 48 thereafter pivots about its lower end in a counterclockwise direction to eifect unseating of the pilot supply valve 25.

Upon the unseating of the pilot supply valve 25, the main supply valve 24 is unloaded, that is the fluid under pressure in the chamber 34 is released past the pilot supply valve 25 to the pressure chamber I9. The choke 35 restricts the flow of fluid to the chamber 34 to a relatively slow rate and thus a reduction of pressure on the back side Aof the main supply valve, that is, unloading of the supply valve is effected.

Following the unloading of the main supply valve 24 in the manner just described, continued movement of the plunger 49 in the left-hand direction causes the spacer rod 51 to engage and unseat the main supply valve 24. Fluid under pressure isaccordingly supplied from the reservoir I2 to the pressure chamber I9 and the Yconnected chamber 65. Accordingly, the pressure of the fluid in the chamber 65 acts in the righthand direction to oppose the force exerted in the left-hand direction. ien the pres.- sure established in the pressure chamber I9 and the chamber 55 substantially balances the force urging the plunger 159 in the left-hand direction, the spring 52 acts to shift the plunger lli in the right-hand direction. The lever d8 is then. pivoted on the plunger 49 in a clockwise direction by the force of the springs 2S and 33 which act to reseat the main supply valve and the pilot supply valve, respectively. Since the pilot release valve E1 and the main release valve 2t are both seated, the pressure established in the pressure chamber I9 is effective to maintain them seated and the rocking of the lever i8 on the plunger 49 tends to assist in maintaining the pilot release valve 21 and main release valve 2S seated.

When the plunger 49 is shifted in the righthand direction suii'iciently for the upper end of the lever i3 to reengage stop screw 53, the main supply valve 2li and the pilot supply valve 25 are again both seated and thus the supply of fluid under pressure to the pressure chamber lll is cut o or lapped.

If the force urging the plunger 49 of the relay valve device ll in the left-hand direction is subsequently reduced, the spring 52 becomes effective to urge the plunger lli in the right-hand direction to a further extent toward its normal position shown in the drawing. Accordingly, since the upper end of the lever engages the stop screw 53, plunger it following lapping of the supply of fluid to the pressure chamber lll causes the lever 18 to pivot about its upper end in a counterclockwise direction and thus eiect the unseating of the pilot release valve 27.

Upon the unseating of the pilot release valve 2l, fluid under pressure from the pressure chamber lil ilows through the central longitudinal passage in the stem of the main release valve 2S to the chamber l5 at the end of the release valve and thus balances the force of the pressiue in the chamber i9 tending to maintain the .main release valve 26 seated so that the main release valve may thereafter be unseated with a relatively small force.

As the movement of the plunger GS in the right-hand direction toward its normal position continues, after unseating of the pilot release valve 2?, the nut E35 on the end of the rod 'i3 carrying the pilot release vaive 2l 'engages the end of, the main release valve 2G and thereafter the main release valve and the pilot release valve are shifted together, the main release valve being accordingly unseated. Upon the unseating of the main release valve it, fluid under pressure is exhausted to atmosphere from the pressure chamber i9, chamber 65 and brake cylinder lll by way of the exhaust passage and port il.

The supply of fluid under pressure to and the release of fluid under pressure from the chamber 69 between the diaphragms il?. and t3 is under the control of the self-lapping brake valve device l. Brake valve device i3 is of the selflapping type, described in detail and claimed in Patent 2,042,112 of Ewing K. Lynn and Rankin J.

continued movement of the pressure is supplied from the reservoir l2 through the pipe and passage ll to the chamber 5S, the pressure established in the chamber S9 corresponding tothe degree to which the operating handle 99 is shifted out of its normal position. If, for any reason, the pressure in the chamber t9 tends to reduce below a value corresponding to the position of the operating handle Sill, theI brake valve device I3 is automatically operative to supply fluid under pressure to maintain the pressure in the chamber Eig. l

The centrifuge device lil may be of any suitable construction and is illustratively shown as comprising a separable casing inwhich is suitably journaled, as by anti-friction bearings, a shaft lli that is arranged to be driven according to the speed of the vehicle or train in the manner to be presently described.

Suitable centrifuge weights U36 in the form of. iiy-balls, are arranged to be rotated with the shaft m5 by means of suitable struts lili. All ofthe struts llil are pivotally connected at one end tov the weights it., some of the struts yeX- tending in one direction along the shaft 135 and l others extending in the opposite direction along the shaft l5. The opposite ends of some of the struts lill are pivotally connected to projecting lugs H38 formed on the shaft 05 and the other struts ll' are pivotally connected at their opposite ends to a sleeve lll which is slidable along the shaft IE5.

A coil spring l l2, concentrically surrounding the shaft H35 and interposed between the lugs tilt and the sleeve l l I, yieldingly urges the sleeve Il l along the shaft IE5 to an extreme position in engagement with the casing when the shaft IE5 is not rotating or rotating at less than a certain low speed.

Upon an increase in speed of` rotation of shaft |05, the weights Ili move outwardly away from the shaft |05 and thus cause the sleeve lli to be shifted in the right-hand direction along the shaft m5, against the yielding resistance of the spring H2.

The sleeve l I l is frictionlessly connected to the outer end of the lever 'I5 as by two ball-bearing races l I3 disposed in spaced relation in an annular recess or groove on the sleeve lil, between which is retained the end of the lever l5. Accordingly, when the ysleeve l i l shifts in the righthand direction or in the left-hand direction, it

causes a corresponding shifting of the outer endJ of the lever l5. It will thus be apparent that since the centrifugal force urging the centrifuge weights lli@ outwardly varies as the square of. the speed of rotation of shaft it, a force will be exerted on the outer end of the lever "l5 tending to shift it in the right-hand direction with a force which varies as the square of the speed of the car or train according to which the shaft N15 is rotated. Thus the force with which the plunger 49 of the relay valve device ll is urged in the left-hand direction depends, in part, upon the speed of the vehicle car or train, the force being connection, to the supporting rod |2I.

greater at the higher speeds and lower at the lower speeds.

Since operation of the centrifuge device |4 results in the application of a force urging the plunger 40 in the left-hand direction and consequently the operation of the valve portion of the relay valve device to supply fluid under pressure to the pressure chamber I9 and the connected brake cylinder I0, it is necessary to provide some automatically operative means for causing the centrifuge device i4 to be operated only during applications of the brakes. Such a mechanism is illustratively shown in Fig. 2 and includes a clutch mechanism for connecting the shaft |05 to an axle ||6 of a vehicle Wheel ||'I. As shown, a friction Wheel I I3 is fixed to the axle I|6 and a friction wheel H9 is arranged to be moved into engagement With the Wheel I8 as by a supporting rod |2| on which the wheel H9 is rotatably mounted, the rod |2| being pivoted on an extended portion of the shaft |05 of. the centrifuge device |4 which is in turn suspended from a fixed part |22 of the vehicle or of the car truck.

The shaft |05 of the centrifuge device I4 is arranged to be driven according to the rotation of the friction Wheel I9 as by an endless chain |23 connecting a sprocket wheel |24 xed to the shaft |05 and a similar sprocket Wheel |25 fixed to or in some manner rotatable with the friction Wheel |I9.

The supporting rod |21 is normally biased by a tension spring |26 connected at opposite ends to the rod |2| and the fixed part |22 of the vehicle truck to a normal position in which the friction wheel i9 is out of engagement with the friction wheel IIB. The supporting rod |2| is arranged to be rocked on the shaft |05, against the yielding resistance of the spring |25, to effect frictional engagement of the two friction wheels ||9 and H8 upon an application of the brakes, as by a cable |21 connected at one end to a brake operating lever |28 actuated by the brake cylinder and at the opposite end, through a yielding A. pulley wheel |3I, rotatably supported cn the fixed part |22 of the vehicle truck, is provided for guiding and tensioning the cable |21.

The tension of the spring |25 is such that the friction wheel H9 is maintained out of engagement With the friction wheel iIS on the Wheel axle ||6 until the fluid pressure established in the brake cylinder I0 exceeds a certain pressure, such as fifteen or twenty pounds per square inch.

Operation Assuming that the main reservoir |2 is charged to the normal pressure carried therein, as from a fluid compresor, in the usual manner and that the vehicle or train of cars is traveling along the road at a relatively high speed with the brake valve handle 99 in its brake release position, the equipment is conditioned as shown in Fig. 1. Obviously, since the pressure in the brake cylinder I0 is below that necessary to effect a driving connection between the wheel axle liti and the shaft of the centrifuge device Ill, the weights |05 of the centrifuge device are not rotated, and, consequently, there is no force exerted on the outer end of the lever 'I5 tending to effect operation of the valve portion of the relay valve device If it is desired to effect an application of the brakes, the operator shifts the brake valve handle 99 into its application zone a desired degree.

Fluid under pressure is accordingly supplied to the chamber 69 between the diaphragms 62 and 63 of the relay valve device I, and the valve portion of' the relay valve device |I is correspondingly operated to supply fluid under pressure to the brake cylinder I0 to establish a pressure therein proportional to the pressure established in the chamber 69. Obviously, the pressure established in the brake cylinder |0 is not equal to the pressure established in the chamber 69 because of the dilerence in the areas of the two diaphragms 6| and 62. If, as assumed previously, the areas of the two diaphragme 6| and 02 have a two-toone'ratio, the pressure established in the brake cylinder solely as a result of the pressure established in the chamber 69 will accordingly be approximately one-half of the pressure established in the chamber 69.

However, when the pressure established in the brake cylinder I0 exceeds that necessary to effect the driving connection between the shaft |05 of the centrifuge device I4 and the Wheel axle H6,

the Weights |06 of the centrifuge device I 4 are rotated at a speed corresponding to vehicle speed and consequently a force is exerted by the centrifuge device |4 in a direction to increase or add to the force of the fluid pressure in the chamber 69 urging the plunger 40 in a left-hand direction. Obviously, the force urging the outer end of the lever 'I5 in the left-hand direction may be suitably amplified by having the lever arm from the pivot pin 9| of the lever 15 to the sleeve of the centrifuge much longer than the lever arm from the pivot pin 0I to the point of connection of the lever 'I5 to the spacer 88 between the diaphragms E33 and 64. For example with a lever arm ratio of live-to-one, the application of one pound of force to the outer end of the lever 'I5 will cause the application of five pounds of force urging the plunger 49 in the left-hand direction.

It should be noted that the force of the huid pressure in the chamber 59 acting on the diaphragm S3 and tending to oppose the force exerted by the centrifuge device I4 is balanced by an equal and opposite force of uid pressure in the chamber 'Il acting on the diaphragm 64, due to the connection between the chambers 69 and through the passage '|2. Thus, the fluid pressure established in the chamber 09 is ineffective to diminish the force exerted by the centrifuge device I4 to urge the plunger 49 of the relay valve device in the left-hand direction.

It should now be apparent that the centrifuge |4 may be so designed in relation to the relay valve device that, assuming a pressure of eighty pounds per square inch to be established in chamber 69 at a predetermined high speed such as one hundred miles per hour, the force exerted by the centrifuge will assist the pressure of the uid in the chamber 69 to urge the plunger 49 in the left-hand direction to such an extent that a fluid pressure of eighty pounds per square inch will be established in the brake cylinder instead of the forty pounds per square inch which would result due solely to the effect of the pressure established in the chamber 59.

The parts may be so designed that as the speed of the vehicle or train reduces due to the application of the brakes, the force exerted by the centrifuge device I4 reduces according to the square of the vehicle speed. It will thus be apparent that When the vehicle has reduced to one-half the speed at the time the application of the brakes was initiated, the force exerted by the centrifuge urging the plunger 49 of the relay valve device in the left-hand direction will be one-fourth of that at the time the application was initiated. In such case, with fluid at eighty pound per square inch pressure in chamber 69, the relay valve device Il is operative to effect a reduction of the pressure in the brake cylinder il to a value which may be fifty pounds per square inch, as compared to t e forty pounds per square inch due solely to the pressure in the chamber 59.

As the vehicle or train continues to reduce in speed due to the application of the brakes, it will be apparent that a point will be reached at which the effect of the force exerted by the centrifuge device will be negligible, such a point conceivably occurring at a speed of, for example twenty-five miles per hour. At this time, therefore, the pressure established in the brake cylinder i@ will be that due substantially only to the pressure established in the chamber 69 and thus, under the assumed conditions, a pressure of approximately forty pounds per square inch will be established in the brake cylinder.

When the vehicle or train comes to a complete stop, the brake valve handle 99 being allowed to remain in its application position, the centrifuge i4 exerts no force on the plunger ll and consequently the pressure established in the brake cylinder is that due solely to the pressure in the chamber 59, which is substantially forty pounds per square inch.

To effect release of the brakes before again starting the vehicle or train, the operator merely shifts the brake valve handle 99 to its release position and thus exhausts iiuid under pressure from the chamber 69 and the connected chamber 1i. Accordingly, the valve portion of the relay valve device il operates in the manner previously described for a reduction of the force urging the plunger i9 in the left-hand direction to effect the complete exhaust of fluid under pressure from the brake cylinder It and consequently the complete release of the brakes. When the pressure in the brake cylinder I reduces suiiiciently, the spring 26 becomes effective to disengage the friction wheel H9 from the friction wheel H8 on the wheel axle H6 and accordingly when the vehicle again is in motion, the centrifuge i4 is not operated.

It will be apparent that the operator may vary the pressure in the chamber S9 at any time during an application of the brakes, to correspondingly vary the degree of the pressure established in the brake cylinder IG, by merely shifting the brake valve handle i3 away from or toward its normal release position, the pressure in the brake cylinder Hl being correspondingly increased or decreased, respectively.

Summary summarizing, it will be seen that I have disclosed a novel brake equipment, for a vehicle or train of cars` comprising essentially a iiuid pressure operated self-lopping relay valve device controlling brake cylinder pressure and a centrifuge device operated according to the speed of the vehicle or train to exert an operating force on the relay Valve device in addition to that of the operating fiuid pressure under the control of the operator. By this arrangement, that is simultaneous manual control of a relay valve device by the operator and automatic control accordingto the speed of the vehicle, the operator may select a desired degree of application and this degree will be automatically reduced as the speed of the vehicle reduces, thereby preventing excessive application of the brakes at the lower speeds and thereby preventing sliding of the vehicle wheels. A clutch arrangement between the centrifuge and a wheel axle is provided for preventtween the movable elements of the centrifuge and the force applying diaphragm of the relay valve device so that the force exerted by the centrifuge varies as the square of the speed, it will be apparent that intervening cam mechanism maybe provided between the centrifuge and the actuating lever for the relay valve device so that the variation in the force applied by the centrifuge device may be according to a straightline or other suitable relation to the variation in the vehicle speed, if desired. It will also be apparent that various other modifications, omissions or additions may be made in the embodiment shown without departing from the-spirit of my invention. It is accordingly not my intention to limit the scope of my invention except as it is necessitated by the scope of the prior art.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A vehicle brake equipment comprising a brake cylinder, a self-lapping valve mechanism including a movable abutment subject in opposing relation to a control fluid pressure and to brake cylinder pressure, said valve mechanism being operative in response to the control fluid pressure acting 0n the abutment to establish a fluid pressure in the brake cylinder corresponding to said control pressure, a second abutment unconnected with the first said abutment and movable in a direction to exert a force on the first said abutment supplementing that of the control fluid pressure, and means controlled by the speed of the vehicle for effecting movement of said second abutment in said direction.

2. A control valve device comprising a first chamber and a second chamber, valve mechanism operative in response to the pressure of fluid .in said second chamber for establishing a corresponding fluid pressure in said first chamber, and movable abutment means subject in balanced relation to the fluid pressure in said second chamber and shiftable in a direction to supplement the effect of the fluid pressure in said second chamber for controlling the operation of the valve mechanism.

3. In combination, a control valve device comprising a first chamber and a second chamber,v

valve mechanism operative in response to the pressure of iiuid in said second chamber for establishing a corresponding fluid pressure in the first said chamber, movable abutment means subject in balanced relation to the fluid pressure in said second chamber and shiftable in a direction to supplement the effect of the fluid pressure in the said second chamber for controlling the operation of the valve mechanism, and automatically controlled means for shifting said movable abutment in said direction.

4. A vehicle brake equipment comprising a brake cylinder, valve mechanism having a chamber and operative in response to the pressure of fluid in said chamber for establishing a corresponding fluid pressure in the brake cylinder, movable abutment means subject in balanced relation to the fluid pressure in said chamber andk shiftable in a direction to supplement the effect of the fluid pressure in the said chamber for controlling the operation of the valve mechanism, and a centrifuge device operative according to the speed of the vehicle for shifting said abutment in said direction.

5. Vehicle brake apparatus comprising a brake cylinder, self-lapping valve means having an operating abutment subject in opposing relation to a control fluid pressure and to brake cylinder pressure for controlling the pressure in the brake cylinder according to the control fluid pressure, a pair of abutments of equal effective pressure areas arranged in coaxial spaced relation to each other, a rigid element connecting said pair of abutments, said pair of abutments being subject in balanced relation on the outer faces thereof to the control fluid pressure, a lever associated with said element at a point between said pair of abutments and operative to move the pair of abutments in a direction to exert a force on said operating abutment in the same -direction as the force of the control fluid pressure, and a centrifuge device operative according to the speed of rotation of a Vehicle Wheel for exerting a moving force on said lever varying With the speed of rotation of the vehicle Wheel.

CLYDE C. FARMER. 

